How to adjust edit view settings?
In my answer I assume that you are already aware of different visualization modes in the viewport by pressing z (wireframe mode) and pressing alt+z to switch back and cycle between Textured and solid mode as for shift+z for render mode.

An alternative way to get semi transparent objects in your viewport is to change the Material's Settings > Viewport Color.

So create a new material for your object and its Material Tab > Settings > Viewport Color set the color (with the alpha transparency) of your choice.

Then go to Mesh Tab > Display and enable Wire to have the closest you can get to an outline.

Important note, is to set your render to Cycles in order to have access to these material's settings.

see the image below: